| 摘要 |
An all-digital communication system is arranged to exhibit fail-safe qualities. Each message includes a pair of words, each word separated from every other word by framing information in the form of two bits, either 1/0 or 0/1. Each word in the message is arranged to exhibit a constant ratio of 1's to 0's, so that more than a single change in any bit location is needed to change from one valid message word to another. The second word in each message is the complement of the first. Two decoders are disclosed, a hard-wired embodiment and an embodiment employing a microprocessor. In the hard-wired embodiment, straightforward decoding is employed to determine the apparent message, and the apparent message is encoded to generate a locally generated message which is then compared, bit by bit, with the received message employing vital logic techniques. Assuming each of the received and locally generated bits compare, the message is validated.
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